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1.
Vaccines (Basel) ; 10(7)2022 Jun 28.
Article in English | MEDLINE | ID: covidwho-1911730

ABSTRACT

Waning immunity following administration of mRNA-based COVID-19 vaccines remains a concern for many health systems. We undertook a study to determine if recent reports of waning for severe disease could have been attributed to design-related bias by conducting a study only among those detected with a first SARS-CoV-2 infection. We used a matched case-control study design with the study base being all individuals with first infection with SARS-CoV-2 reported in the State of Qatar between 1 January 2021 and 20 February 2022. Cases were those detected with first SARS-CoV-2 infection requiring intensive care (hard outcome), while controls were those detected with first SARS-CoV-2 infection who recovered without the need for intensive care. Cases and controls were matched in a 1:30 ratio for the calendar month of infection and the comorbidity category. Duration and magnitude of conditional vaccine effectiveness against requiring intensive care and the number needed to vaccinate (NNV) to prevent one more case of COVID-19 requiring intensive care was estimated for the mRNA (BNT162b2/mRNA-1273) vaccines. Conditional vaccine effectiveness against requiring intensive care was 59% (95% confidence interval (CI), 50 to 76) between the first and second dose, and strengthened to 89% (95% CI, 85 to 92) between the second dose and 4 months post the second dose in persons who received a primary course of the vaccine. There was no waning of vaccine effectiveness in the period from 4 to 6, 6 to 9, and 9 to 12 months after the second dose. This study demonstrates that, contrary to mainstream reports using hierarchical measures of effectiveness, conditional vaccine effectiveness against requiring intensive care remains robust till at least 12 months after the second dose of mRNA-based vaccines.

2.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-334155

ABSTRACT

ABSTRACT Background Waning immunity following administration of mRNA based COVID-19 vaccines remains a concern for many health systems. We undertook a study of SARS-CoV-2 infections, with and without requirement for intensive care to shed more light on the duration of vaccine effectiveness for protection against the need for intensive care. Methods We used a matched case-control study design with the study base being all individuals with first infection with SARS-CoV-2 reported in the State of Qatar between 1 Jan 2021 and 20 Feb 2022. Cases were those requiring intensive care while controls were those who recovered without need for intensive care. Vaccine effectiveness against requiring intensive care and number needed to vaccinate (NNV) to prevent one more case of COVID-19 requiring intensive care were computed for the mRNA (BNT162b2 / mRNA-1273) vaccines. Results Vaccine effectiveness against requiring intensive care was 59% (95% confidence interval [CI], 50 to 76) between the first and second dose and strengthened to 89% (95% CI, 85 to 92) between the second dose and 4 months post the second dose in persons who received a primary course of the vaccine. There was no waning of vaccine effectiveness in the period from 4 to 12 months after the second dose. Conclusions This study demonstrates that vaccine effectiveness against requiring intensive care remains robust till at least 12 months after the second dose of mRNA based vaccines.

3.
Pathog Glob Health ; 116(5): 269-281, 2022 07.
Article in English | MEDLINE | ID: covidwho-1662085

ABSTRACT

This study aims to estimate the prevalence and longevity of detectable SARS-CoV-2 antibodies and T and B memory cells after recovery. In addition, the prevalence of COVID-19 reinfection and the preventive efficacy of previous infection with SARS-CoV-2 were investigated. A synthesis of existing research was conducted. The Cochrane Library, the China Academic Journals Full Text Database, PubMed, and Scopus, and preprint servers were searched for studies conducted between 1 January 2020 to 1 April 2021. Included studies were assessed for methodological quality and pooled estimates of relevant outcomes were obtained in a meta-analysis using a bias adjusted synthesis method. Proportions were synthesized with the Freeman-Tukey double arcsine transformation and binary outcomes using the odds ratio (OR). Heterogeneity was assessed using the I2 and Cochran's Q statistics and publication bias was assessed using Doi plots. Fifty-four studies from 18 countries, with around 12,000,000 individuals, followed up to 8 months after recovery, were included. At 6-8 months after recovery, the prevalence of SARS-CoV-2 specific immunological memory remained high; IgG - 90.4% (95%CI 72.2-99.9, I2 = 89.0%), CD4+ - 91.7% (95%CI 78.2-97.1y), and memory B cells 80.6% (95%CI 65.0-90.2) and the pooled prevalence of reinfection was 0.2% (95%CI 0.0-0.7, I2 = 98.8). Individuals previously infected with SARS-CoV-2 had an 81% reduction in odds of a reinfection (OR 0.19, 95% CI 0.1-0.3, I2 = 90.5%). Around 90% of recovered individuals had evidence of immunological memory to SARS-CoV-2, at 6-8 months after recovery and had a low risk of reinfection.RegistrationPROSPERO: CRD42020201234.


Subject(s)
COVID-19 , Adaptive Immunity , COVID-19/epidemiology , Humans , Prevalence , Reinfection/epidemiology , SARS-CoV-2
4.
2021.
Preprint in English | Other preprints | ID: ppcovidwho-294470

ABSTRACT

Objectives This study aims to estimate the prevalence and longevity of detectable SARS-CoV-2 specific antibodies as well as memory T and B cells after recovery. In addition, the prevalence of COVID-19 reinfection, and the preventive efficacy of previous infection with SARS-CoV-2 were investigated. Methods and analyses A synthesis of existing research was conducted. The Cochrane Library for COVID-19 resources, the China Academic Journals Full Text Database, PubMed, and Scopus as well as preprint servers were searched for studies conducted between 1 January 2020 to 1 April 2021. We included studies with the relevant outcomes of interest. All included studies were assessed for methodological quality and pooled estimates of relevant outcomes were obtained in a meta-analysis using a bias adjusted synthesis method. Proportions were synthesized with the Freeman-Tukey double arcsine transformation and binary outcomes using the odds ratio (OR). Heterogeneity between included studies was assessed using the I 2 and Cochran’s Q statistics and publication bias was assessed using Doi plots. Results Fifty-four studies, from 18 countries, with a total of 12 011 447 individuals, followed up to 8 months after recovery, were included. At 6-8 months after recovery, the prevalence of detectable SARS-CoV-2 specific immunological memory remained high;IgG – 90.4% (95%CI 72.2-99.9, I 2 =89.0%, 5 studies), CD4+ - 91.7% (95%CI 78.2 – 97.1, one study), and memory B cells 80.6% (95%CI 65.0-90.2, one study) and the pooled prevalence of reinfection was 0.2% (95%CI 0.0 – 0.7, I 2 = 98.8, 9 studies). Individuals who recovered from COVID-19 had an 81% reduction in odds of a reinfection (OR 0.19, 95% CI 0.1 - 0.3, I 2 = 90.5%, 5 studies). Conclusion Around 90% of people previously infected with SARS-CoV-2 had evidence of immunological memory to SARS-CoV-2, which was sustained for at least 6-8 months after recovery, and had a low risk of reinfection. Registration PROSPERO: CRD42020201234

6.
Epidemiol Infect ; 149: e193, 2021 07 02.
Article in English | MEDLINE | ID: covidwho-1366777

ABSTRACT

There is a paucity of evidence about the prevalence and risk factors for symptomatic infection among children. This study aimed to describe the prevalence of symptomatic coronavirus disease 2019 (COVID-19) and its risk factors in children and adolescents aged 0-18 years in Qatar. We conducted a cross-sectional study of all children aged 0-18 years diagnosed with COVID-19 using polymerase chain reaction in Qatar during the period 1st March to 31st July 2020. A generalised linear model with a binomial family and identity link was used to assess the association between selected factors and the prevalence of symptomatic infection. A total of 11 445 children with a median age of 8 years (interquartile range (IQR) 3-13 years) were included in this study. The prevalence of symptomatic COVID-19 was 36.6% (95% confidence interval (CI) 35.7-37.5), and it was similar between children aged <5 years (37.8%), 5-9 years (34.3%) and 10 + years (37.3%). The most frequently reported symptoms among the symptomatic group were fever (73.5%), cough (34.8%), headache (23.2%) and sore throat (23.2%). Fever (82.8%) was more common in symptomatic children aged <5 years, while cough (38.7%) was more prevalent in those aged 10 years or older, compared to other age groups. Variables associated with an increased risk of symptomatic infection were; contact with confirmed cases (RD 0.21; 95% CI 0.20-0.23; P = 0.001), having visited a health care facility (RD 0.54; 95% CI 0.45-0.62; P = 0.001), and children aged under 5 years (RD 0.05; 95% CI 0.02-0.07; P = 0.001) or aged 10 years or older (RD 0.04; 95% CI 0.02-0.06; P = 0.001). A third of the children with COVID-19 were symptomatic with a higher proportion of fever in very young children and a higher proportion of cough in those between 10 and 18 years of age.


Subject(s)
COVID-19/epidemiology , Cough/epidemiology , Fever/epidemiology , Headache/epidemiology , Pharyngitis/epidemiology , Adolescent , COVID-19/virology , Child , Child, Preschool , Cross-Sectional Studies , Female , Humans , Infant , Infant, Newborn , Male , Qatar/epidemiology , Risk Factors
7.
Travel Med Infect Dis ; 43: 102135, 2021.
Article in English | MEDLINE | ID: covidwho-1307224

ABSTRACT

OBJECTIVE: To synthesize findings from systematic reviews and meta-analyses on the efficacy and safety of chloroquine (CQ) and hydroxychloroquine (HCQ) with or without Azithromycin for treating COVID-19, and to update the evidence using a meta-analysis. METHODS: A comprehensive search was carried out in electronic databases for systematic reviews, meta-analyses and experimental studies which investigated the efficacy and safety of CQ, HCQ with or without Azithromycin to treat COVID-19. Findings from the reviews were synthesised using tables and forest plots and the quality effect model was used for the updated meta-analysis. The main outcomes were mortality, the need for intensive care services, disease exacerbation, viral clearance and occurrence of adverse events. RESULTS: Thirteen reviews with 40 primary studies were included. Two meta-analyses reported a high risk of mortality, with ORs of 2.2 and 3.0, and the two others found no association between HCQ and mortality. Findings from two meta-analyses showed that HCQ with Azithromycin increased the risk of mortality, with similar ORs of 2.5. The updated meta-analysis of experimental studies showed that the drugs were not effective in reducing mortality (RR 1.1, 95%CI 1.0-1.3, I2 = 0.0%), need for intensive care services (OR 1.1, 95%CI 0.9-1.4, I2 = 0.0%), virological cure (OR 1.5, 95%CI 0.5-4.4, I2 = 39.6%) or disease exacerbation (OR 1.2, 95%CI 0.3-5.9, I2 = 31.9%) but increased the odds of adverse events (OR 12,3, 95%CI 2.5-59.9, I2 = 76.6%). CONCLUSION: There is conclusive evidence that CQ and HCQ, with or without Azithromycin are not effective in treating COVID-19 or its exacerbation. REGISTRATION: PROSPERO: CRD42020191353.


Subject(s)
COVID-19 , Hydroxychloroquine , Antiviral Agents/therapeutic use , COVID-19/drug therapy , Chloroquine/adverse effects , Humans , Hydroxychloroquine/adverse effects , SARS-CoV-2 , Systematic Reviews as Topic , Treatment Outcome
8.
Front Public Health ; 8: 573925, 2020.
Article in English | MEDLINE | ID: covidwho-1021920

ABSTRACT

Background: SARS-CoV-2 continues to claim hundreds of thousands of people's lives. It mostly affects the elderly and those with chronic illness but can also be fatal in younger age groups. This article is the first comprehensive analysis of the epidemiological and clinical outcomes of the travel-associated SARS-CoV-2 cases until April 19, 2020. Methods: Demographic and clinical data of travel-associated SARS-CoV-2 cases were collected for the period between January 16, 2020 and April 19, 2020. More than one hundred and eighty databases were searched, including the World Health Organization (WHO) database, countries' ministries websites, and official media sites. Demographic and clinical data were extracted and analyzed. Results: A total of 1,186 cases from 144 countries meeting the inclusion criteria were reported and included in the analysis. The mean age of the cases was 44 years, with a male to female ratio of 1.6:1. Travel-associated cases originated from more than 40 countries, with China, Italy, and Iran reporting the highest numbers at 208, 225, and 155, respectively. Clinical symptoms varied between patients, with some reporting symptoms during the flights (117 cases; 9.87%). A total of 312 (26.31%) cases were hospitalized, of which 50 cases (4.22%) were fatal. Conclusion: Major gaps exist in the epidemiology and clinical spectrum of the COVID-19 travel-associated cases due to a lack of reporting and sharing data of many counties. The identification and implementation of methodologies for measuring traveler's risk to coronavirus would help in minimizing the spread of the virus, especially in the next waves.


Subject(s)
COVID-19 , Demography , Infection Control , Travel , Adult , COVID-19/diagnosis , COVID-19/epidemiology , China/epidemiology , Female , Humans , Iran/epidemiology , Italy/epidemiology , Male , SARS-CoV-2/isolation & purification
9.
BMJ Open ; 10(12): e041761, 2020 12 15.
Article in English | MEDLINE | ID: covidwho-978807

ABSTRACT

OBJECTIVE: People with diabetes mellitus have a high risk of acquiring respiratory tract infections (RTIs), yet little is known about their utilisation of healthcare services compared with people without diabetes. This study aimed to compare the utilisation of healthcare services for RTIs between individuals with and without diabetes attending primary healthcare centres (PHCCs) in Qatar. DESIGN: A retrospective cross-sectional study was conducted using an electronic database of all individuals who had a diagnosis of RTI. SETTING: PHCCs in Qatar from July 2015 to December 2017. PARTICIPANTS: Participants in the study were all adult individuals (aged ≥18 years) who visited the primary healthcare facilities and were diagnosed with an RTI during the study period. PRIMARY AND OUTCOME MEASURES: For each participant, visits to the healthcare facility, antibiotic use and use of other medications were extracted from the electronic database and compared between participants with and without a diabetes diagnosis. RESULTS: A total of 32 857 participants were included, of whom 7407 (22.5%) had a diabetes diagnosis. Results from a negative binomial regression indicate that diabetes diagnosis was significantly associated with increased visits to the healthcare facility (incidence rate ratio (IRR) 1.10, 95% CI 1.076 to 1.134, p<0.001), antibiotic use (IRR 1.09, 95% CI 1.046 to 1.145, p<0.001) and use of other medications (IRR 1.11, 95% CI 1.078 to 1.143, p<0.001). CONCLUSIONS: A diabetes diagnosis among patients with RTI was associated with higher utilisation of healthcare services. Given the added costs to the healthcare system, prevention of diabetes will have additional benefits to the healthcare system, apart from diabetes-associated costs alone.


Subject(s)
Diabetes Mellitus , Respiratory Tract Infections , Adolescent , Adult , Cross-Sectional Studies , Delivery of Health Care , Diabetes Mellitus/epidemiology , Diabetes Mellitus/therapy , Humans , Qatar/epidemiology , Respiratory Tract Infections/drug therapy , Respiratory Tract Infections/epidemiology , Retrospective Studies
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